Nutrition in the run up to tupping is critical to ensure success. Every year farmers spend money on various supplements for their ewes – often without knowing what they actually require.
Here Rachel Mallet, who works as a Professional Services Vet in the UK, looks at the important steps to get right with trace element nutrition.
“To guarantee optimum nutrition you should be working with your vet to determine the current trace element status of your flock. He/she can then advise which trace elements, if any, are required,” she said.
Copper
Mallet added: “Copper plays a vital role in the health and fertility of sheep. It’s needed for the production of enzymes that are required for fertility and thrive, as well as for healthy wool and white blood cell function.
“White blood cell function is vital to the immune system which defends the sheep against disease and parasites.”
Furthermore, during gestation the ewe requires copper to develop the lamb’s nervous system. Without an adequate source of copper mid-pregnancy the lamb’s nervous system is not formed correctly and cannot be treated – this is known as swayback.
“Copper should never be supplemented without first consulting a vet to establish that there is a need, as excess copper can result in copper toxicity which can prove fatal.
“Housed sheep, sheep which are due to be housed within the next six months and continental breeds are particularly susceptible to copper toxicity,” she warned.
The below table highlights how susceptible some of the most common breeds are to copper toxicity:
Mallet continued: “While copper deficiency can be caused by insufficient copper in the sheep’s diet, this is actually relatively rare.
“It is far more likely that sheep are ingesting adequate levels of copper; but that they are also ingesting high levels of other elements which either antagonise copper or cause harm after absorption.”
Cobalt is required by the rumen microbes for the production of Vitamin B12, which is important for thrive and fertility, explained Mallet.
“Cobalt is also critical for growth in lambs.
The body has no capacity to store cobalt; therefore it must be continuously supplied. This means that a cobalt drench is not suitable to address an established cobalt deficiency. “While drenches can be cheap and convenient, they are also a false economy to treat established cobalt deficiency. The excess cobalt cannot be stored and simply passes out of the animal in faeces.”
Instead, a slow-release, continuous supply form of supplementation should be used – such as a bolus.
The vet added: “Selenium is vital for muscle function and deficiency can result in white muscle disease.
“Selenium deficiency is also a cause of impaired fertility, impaired growth, poor wool quality and reduced immunity.”
“Like cobalt, iodine is a trace element that ruminants have no capacity to store and a continuous supply must therefore be available,” she said.
“Where the animal’s diet is unable to provide this, supplementation will be required.
“Where a deficiency has been identified and requires supplementation, I would always advocate in favour of supplementation which supplies trace elements at a controlled and constant rate over long periods – making boluses particularly suitable.”
“Furthermore, ewes will not be able to transfer sufficient amounts of the element to the unborn lamb. This can result in lambs being born weak or dead,” Mallet added.
“Trace element status will vary from farm to farm and even from field to field. There is no way to know which deficiencies or toxicities exist unless you carry out the diagnostics.
“The best way to determine this is by blood sampling a number of the ewes and taking samples of the forage they are consuming. Your vet can advise how many samples are required,” she said.
If trace element imbalances are present in your flock, she said, you need to implement any dietary changes at least four weeks prior to tupping to ensure the full benefit of correcting the diet.
“As such, blood sampling ewes and collection of forage samples should be carried out six-to-eight weeks before tupping. This allows plenty of time to get the results back and implement any changes.”
“If your vet diagnoses a trace element deficiency, and has advised you to supplement trace elements, you have a number of options,” she said.
Mallet said that drenches can seem like a cheap and convenient option.
“However, for trace elements which cannot be stored in the body, such as cobalt or iodine, they are not appropriate to treat deficiencies – a continuous form of supplementation must be supplied.
If you provide cobalt via a drench, the excess that the body cannot use will simply be passed out in the faeces. “This means that they are in fact a false economy for the farmer. Frequent dosing is required. This increases costs to the farmer, both in terms of the drench itself and labour required.”
She continued: “We need to ensure that all animals receive an amount of trace elements which is compatible with their daily requirements.
“Too much of a trace element can prove toxic; too little and the deficiency will not be addressed.
“Unfortunately, the free access lick and block systems do not provide this guarantee and an independent study highlighted that intakes between animals are extremely variable, with some consuming nothing and others consuming excessive quantities.¹
“In another study, 50% of ewes were shown not to consume any supplement at all.² Therefore, a more scientific approach to supplementation is required,” she added.
“Injections can be suitable for targeted administration in conjunction with the advice of your vet. They can be appropriate where only a single trace element, such as copper, is required.”
“Like blocks and licks, these forms of supplementation suffer from variable intakes. It is also difficult in practice for hill sheep, due to the extensive nature of hill sheep production.”
“Trace elements can be provided by the provision of total mixed ration (TMR), concentrates or bagged minerals,” she said.
Often these are specified based on ‘averages’ or ‘common requirements’ as opposed to being based on what has been determined is deficient and required on-farm. “Ideally these mixes should be prepared based on an investigation to address the animals’ specific trace element requirements.
“This method can add significantly to the cost of production and can be difficult for hill sheep due to extensive conditions.”
On trace element boluses, she said: “Boluses provide a convenient and controlled method of trace element supplementation. This means there are no variable intakes and no guesswork for the farmer.
“This is particularly important for animals requiring cobalt and iodine which cannot be stored in the body and therefore a daily supply is required.
“Their long-lasting nature is also highly convenient and reduces labour costs as regular bolusing is not required.
“Only the Cosecure and CoseIcure boluses supply rumen available ionic copper and cobalt. The most important thing to remember is to ensure that a need for trace element supplementation has been established before supplying any form,” Mallet concluded.
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References
Cobalt
Selenium
Iodine
What action should I take for my flock?
When should I take action?
Which product is right for my flock?
Oral drenches
Free access systems, such as licks and blocks
Injections
Pasture dressing and water supplementation
In feed supplementation
Trace element boluses
